It adds up

Decades ago I heard someone from IBM project computer size. In the 1950s, he said, it took a whole building to house one that punched holes in cards. In the 1960s, a computer would fit into a single room, duly air-conditioned. By the 1970s the reductions would continue, and a computer would fit on a desk. By the 1980s the laptop would take over, and in the 1990s you would wear your computer. In 2000? He said that the only problem with further reduction was the size of our fingers and the sharpness of our eyes. In theory, a computer need be only one neutron wide.